Mobile communication systems have evolved over the past ten years or so from the GSM System (Global System for Mobiles) to the 3G system and now include packet data communications as well as circuit switched communications. The third generation project partnership (3GPP) has now began to develop a mobile communication system referred to as Long Term Evolution (LTE) in which a core network part has been evolved to form a more simplified architecture based on a merging of components of earlier mobile radio network architectures and a radio access interface which is based on Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) on the uplink.
It is known within the 3GPP standards, such as the LTE standards to provide a co-operating set of a plurality of base stations which co-operate in order to communicate data to a communications terminal. The co-operating set of base stations includes a serving base station and at least one co-operating base station. The serving base station is a base station to which the communications terminal is attached in the sense that control and signalling of radio bearers are established with the serving base stations as well as the S1-U and S1-MME connections with the serving gateway and mobility manager via the serving base station respectively. The serving base station is typically configured to control the communication of the user data to the co-operating base station via an interface between the serving base station and the co-operating base station. The serving base station can then control the communication of user data selectively to the communications terminals from either the serving base station or the co-operating base station or both depending on a state of a radio communications link between the co-operating base station and the communications terminals and the radio communication techniques which are used to form the wireless access interface between the base stations and the communications terminals.
As will be appreciated it is generally desirable to provide a mobile communications system and network which can operate efficiently in order to optimise the use of communications resources and infrastructure equipment.